autofs-5.1.7 - use snprintf() when constructing hosts mapent

From: Ian Kent <raven@themaw.net>

Using multiple strcpy() and strcat() functions when constructing the
hosts map offset for each export is much slower than using a single
sprintf() for each.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG              |    1 +
 modules/lookup_hosts.c |   26 +++++++++++++-------------
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 1bd6ac7f..d613e5ca 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,7 @@
 - add xdr_exports().
 - remove mount.x and rpcgen dependencies.
 - dont use realloc in host exports list processing.
+- use sprintf() when constructing hosts mapent.
 
 25/01/2021 autofs-5.1.7
 - make bind mounts propagation slave by default.
diff --git a/modules/lookup_hosts.c b/modules/lookup_hosts.c
index e3ee0ab8..c1ebb7f6 100644
--- a/modules/lookup_hosts.c
+++ b/modules/lookup_hosts.c
@@ -87,10 +87,12 @@ int lookup_read_master(struct master *master, time_t age, void *context)
 static char *get_exports(struct autofs_point *ap, const char *host)
 {
 	char buf[MAX_ERR_BUF];
+	char entry[PATH_MAX + 1];
 	char *mapent;
 	struct exportinfo *exp, *this;
 	size_t hostlen = strlen(host);
 	size_t mapent_len;
+	int len, pos;
 
 	debug(ap->logopt, MODPREFIX "fetchng export list for %s", host);
 
@@ -114,21 +116,19 @@ static char *get_exports(struct autofs_point *ap, const char *host)
 	}
 	*mapent = 0;
 
+	pos = 0;
 	this = exp;
-	while (this) {
-		if (!*mapent)
-			strcpy(mapent, "\"");
-		else
-			strcat(mapent, " \"");
-		strcat(mapent, this->dir);
-		strcat(mapent, "\"");
-
-		strcat(mapent, " \"");
-		strcat(mapent, host);
-		strcat(mapent, ":");
-		strcat(mapent, this->dir);
-		strcat(mapent, "\"");
+	if (this) {
+		len = sprintf(mapent, "\"%s\" \"%s:%s\"",
+				this->dir, host, this->dir);
+		pos += len;
+		this = this->next;
+	}
 
+	while (this) {
+		len = sprintf(mapent + pos, " \"%s\" \"%s:%s\"",
+				this->dir, host, this->dir);
+		pos += len;
 		this = this->next;
 	}
 	rpc_exports_free(exp);